vz: build fix for virdomainsnapshotobjlist.h

Commit [1] moved snapshot list functions declaration into
its own file but missed a fix for vz driver.

[1] 9b75154c : snapshot: Break out virDomainSnapshotObjList into its own file
Signed-off-by: NNikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>

src/vz/vz_utils.h

@@ -28,6 +28,7 @@
 # include "driver.h"
 # include "conf/domain_conf.h"
 # include "conf/snapshot_conf.h"
+# include "conf/virdomainsnapshotobjlist.h"
 # include "conf/virdomainobjlist.h"
 # include "conf/domain_event.h"
 # include "virthread.h"